Future 5G cellular networks are expected to support a range of use cases, spanning different vertical industries. It is likely that not all of these use cases will share the same service requirements. It is likely that the traditional ‘one-size-fits-all’ cellular approach will not allow to reliably fulfil these service requirements. Therefore, one of the key challenge for 5G networks is how one network, based on a common physical infrastructure, can be efficiently shared among different vertical application sectors.
The industry presently believes that ‘network slicing’ is likely to be indispensable in future 5G cellular networks in order to provide the required design flexibility. Network slicing creates multiple logical networks over a common physical infrastructure. Each of these networks is or can be tailored to specific needs of a use case. Network slicing includes slicing of both radio access (wireless) and core (wired) networks.
Radio resource slicing can be enabled through virtualization of radio resources. Such virtualization-based radio resource slicing must be able to achieve tight isolation, provide application-specific customization, and ensure efficient utilization across different radio slices. Compared to virtualization in the wired domain, unique challenges get introduced when virtualizing wireless/radio resources. Firstly, co-existence of bandwidth-based and resource-based reservations is not straightforward. This is because the bandwidth achieved by a slice from a given amount of radio resources directly varies with the channel quality of users. Secondly, the uplink traffic makes it difficult to achieve the conflicting goals of isolation and high-utilization across slices due to the fact that traffic originates at the user devices. Thirdly, wireless networks often incur considerable overhead due to retransmissions which must be properly accounted for as otherwise utilization of a base station would be affected.